Given an array of 0's and 1's your task is to complete the function maxLen which returns size of the largest sub array with equal number of 0's and 1's .
The function maxLen takes 2 arguments .The first argument is the array A[] and second argument is the size 'N' of the array A[] .

Input:
The first line of the input is T denoting the number of test cases .
Then T test cases follow . Each test case contains two lines .
The first line of each test case is a number N denoting the size of the array and in the next line are N space separated values of A [ ].

Output:
For each test case output in a new line the max length of the subarray .

Note:The Input/Ouput format and Example given are used for system's internal purpose, and should be used by a user for Expected Output only. As it is a function problem, hence a user should not read any input from stdin/console. The task is to complete the function specified, and not to write the full code.